Chad has declared a state of emergency in the Lake Chad region after a series of raids and suicide bombings there by militant Islamist group Boko Haram, the government said on Monday.

Chad was instrumental in forcing Boko Haram to cede territory earlier this year, undermining its six-year campaign to carve out a Nigerian caliphate.

But guerrillas have since ramped up attacks in remote border areas around Lake Chad, killing at least three people in a Chadian village on Sunday and three Nigerian refugees in northern Cameroon on Monday.

Chad's Communications Minister Hassan Sylla Bakari said the order, effective immediately, would grant authorities new power to search and monitor residents in the region.

There has not been a state of emergency in Chad, one of Africa's military heavyweights, since a series of rebellions in the 2000s springing from its volatile east. Neighboring Niger also has a state of emergency in its border region of Diffa.

A top U.N. official said last month that an 8,700 regional task force will begin joint raids against Boko Haram when the rainy season ends soon.

Vice Admiral Michael Franken, U.S. Africa Command's Deputy for Military Operations, told Reuters on Monday he expected Nigeria-led actions to lead to a "significant degradation" in Boko Haram's activities within six months.

The United States has sent troops to provide intelligence and other assistance to counter Boko Haram.